Hey guys i am doing my Longtube Header install and Off-road Y-pipe on my 2008 silverado 5.3L, but what has me confused is there is 3 sensor bungs, i know 2 of them are O2 sensor would anyone know what the 3rd sensor is and also would i need to weld a sensor bung in for it cause i only have for 2 sensor on my new LT's and Y-pipe?? I will be doing a tune with the HP Tuners software, i dont know if that will help anyone get me answer on what to do?

 

Are all 3 bungs in the collectors? You're only gonna keep the 2 pre cat o2 sensors. The bottom 2 or post cat you will do away with and tune out. Possibly the 3 rd bung is for a wide band?

 

Well I got my LT installed but now I'm fighting the y-pipe, was I supposed to slip it on before the header gets bolted up??

 

if you can, unbolt the rest of the exhaust so you can slide it rearward. I usually tighten a couple header bolts just by hand so they don't move off the head while putting the rest of the exhaust together.